Carrier circuit boards sometimes equipped with LEDs are screwed to lamp housings in LED retrofit lamps or LED luminaires. This fitting in principle guarantees effective heat transfer from the LED via the carrier circuit board to the housing or heat sink. Even in the case of LED tubes which act as a replacement for the conventional fluorescent tubes, the carrier circuit board equipped with LEDs is often screwed to a lamp housing.
One disadvantage with screw connections consists in that a lamp housing consisting of plastics can break when the screws are tightened excessively. In addition, owing to the drilled holes required for the screw connection, there is the problem of lines running within the heat sink. These lines result in a hazardous mains potential. The insulation of these lines which is intended to protect the user from an electric shock on contact with the heat sink may be damaged by the metal chips resulting during drilling or by the ends of screws.
In addition, the screwing process is very cost-intensive. Also, alternatively, possible adhesive bonds result in a relatively high degree of complexity involved for the application of the adhesive and a time pressure under which the parts need to be joined in order that the adhesive does not dry.